The prior art is replete with portable electronic devices that are powered by rechargeable energy sources such as batteries. Portable consumer grade electronic devices have become ubiquitous in modern society; such devices include digital media players, mobile telephones, personal digital assistants, handheld video games, and the like. Moreover, portable electronic devices are commonly used for medical applications and systems. For example, the following types of medical devices can be implemented in a battery-powered platform: a wearable fluid infusion pump; a portable patient monitor device; a controller for a patient-worn medical device; or the like.
Certain types of rechargeable batteries (e.g., lithium ion and lithium polymer batteries) used in small electronic equipment can be susceptible to damage caused by overcharging or over-discharging (i.e., an undercharge condition). Usually, an external charger component includes the logic, circuits, and hardware needed to prevent an overcharging condition. However, protection against over-discharging is generally considered to be the responsibility of the user or the host device itself. In this regard, supervisory devices or circuits are typically integrated into electronic devices for purposes of monitoring the battery voltage and possibly other state of charge conditions associated with the battery.
A supervisory circuit electrically disconnects the battery from the load when the battery charge is low. Unfortunately, conventional battery supervisory circuits remain electrically connected to the monitored battery, even after the battery has been disconnected from the primary load. In other words, the supervisory circuit itself remains a current-drawing load on the battery even though the battery has been disconnected from the load. Consequently, the supervisory circuit itself can cause the battery to lose charge and voltage over time. As a result, the health and lifespan of the battery can be negatively affected by such a supervisory circuit.